Highly thermostable and crystalline poly(butylene adipate) bionanocomposites prepared by <i>in situ</i> polycondensation with organically modified Moroccan beidellite clay

Abstract

Abstract Bionancomposites from bioplastics and nanoclays are of great interest for packaging, agricultural and other large‐volume and niche applications due to their enhanced physical, thermal, mechanical and processing characteristics compared to the parent polymer. In this study, the biodegradable polyester poly(butylene adipate) ( PBA ) was synthesized by in situ polycondensation catalysed by titanium tetrabutoxide in the presence of the natural Moroccan clay beidellite ( BDT ). Optimization of the nanoclay exfoliation in the bionanocomposite was achieved by cation exchange of BDT with cetyltrimethylammonium bromide ( CTA ) and by selecting the most effective among a range of organically modified x CTA‐BDT ( x = CTA/BDT equivalent feed ratio). Fourier transform infrared and 1 H NMR spectral and size exclusion chromatographic analyses confirmed the effectiveness of the in situ polymerization, yielding structurally regular PBA with narrow molecular weight dispersity and 7750 &lt; &lt; 30 360 g mol −1 , depending on the organoclay load. X‐ray diffraction and transmission electron microscopy analyses showed best clay dispersion and homogeneous distribution at 2 wt% 3CTA‐BDT. From thermogravimetric analysis and differential scanning calorimetry results the thermal stability of PBA is greatly improved even at 1 wt% 3CTA‐BDT, its glass transition temperature is nearly unaffected while crystallinity is increased by the organoclay nucleating action. These results, along with a bionanocomposite hydrophilicity only moderately higher than that of PBA, make this preparation approach particularly promising. © 2017 Society of Chemical Industry